How do you do block comments in YAML?

YAML supports inline comments, but does not support block comments.

From Wikipedia:

Comments begin with the number sign ( # ), can start anywhere on a line, and continue until the end of the line

A comparison with JSON, also from Wikipedia:

The syntax differences are subtle and seldom arise in practice: JSON allows extended charactersets like UTF-32, YAML requires a space after separators like comma, equals, and colon while JSON does not, and some non-standard implementations of JSON extend the grammar to include Javascript's /* ... */ comments. Handling such edge cases may require light pre-processing of the JSON before parsing as in-line YAML.

# If you want to write
# a block-commented Haiku
# you'll need three pound signs

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The spec only describes one way of marking comments:

An explicit comment is marked by a “#” indicator.

That's all. There are no block comments.

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Not trying to be smart about it, but if you use Sublime Text for your editor, the steps are:

Select the block cmd+/ on Mac or ctrl+/ on Linux & Windows Profit

I'd imagine that other editors have similar functionality too. Which one are you using? I'd be happy to do some digging.

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In Vim you can do one of the following:

Comment all lines: :%s/^/#

Comment lines 10 - 15: :10,15s/^/#

Comment line 10 to current line: :10,.s/^/#

Comment line 10 to end: :10,$s/^/#

or using visual block:

Select a multiple-line column after entering visual block via Ctrl+v. Press r followed by # to comment out the multiple-line block replacing the selection, or Shift+i#Esc to insert comment characters before the selection.

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An alternative approach:

If

your YAML structure has well defined fields to be used by your app

AND you may freely add additional fields that won't mess up with your app

then

at any level you may add a new block text field named like "Description" or "Comment" or "Notes" or whatever

Example:

Instead of

# This comment
# is too long

use

Description: >
  This comment
  is too long

or

Comment: >
    This comment is also too long
    and newlines survive from parsing!

More advantages:

If the comments become large and complex and have a repeating pattern, you may promote them from plain text blocks to objects Your app may -in the future- read or update those comments

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For Visual Studio Code (VSCode) users, the shortcut to comment out multiple lines is to highlight the lines you want to comment and then press:

ctrl + /

Pressing ctrl + / again can also be used to toggle comments off for one or more selected lines.

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One way to block commenting in YAML is by using a text editor like Notepad++ to add a # (comment) tag to multiple lines at once.

In Notepad++ you can do that using the "Block Comment" right-click option for selected text.

https://i.stack.imgur.com/AhAQt.png

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Emacs has comment-dwim (Do What I Mean) - just select the block and do a:

M-;

It's a toggle - use it to comment AND uncomment blocks.

If you don't have yaml-mode installed you will need to tell Emacs to use the hash character (#).

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If you are using Eclipse with the yedit plugin (an editor for .yaml files), you can comment-out multiple lines by:

selecting lines to be commented, and then Ctrl + Shift + C

And to un-comment, follow the same steps.

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For Ruby Mine users on Windows:

Open file in editor Select the block and press Ctrl+forward slash, you will have selected block starting with #.

Now if you want to un-comment the commented block, press same key combination Ctrl+forward slash again

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In Azure Devops browser(pipeline yaml editor),

Ctrl + K + C Comment Block

Ctrl + K + U Uncomment Block

https://i.stack.imgur.com/3NusW.png

There are other 'wierd' ways too: right click to see 'Command Palette' or F1

https://i.stack.imgur.com/aFSjJ.png

https://i.stack.imgur.com/iWMVH.png

Now it is just a matter of #

or even smarter [Ctrl + k] + [Ctrl + c]

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In .gitlab-ci.yml file following works::

To comment out a block (multiline): Select the whole block section > Ctrl K C To uncomment already commented out block (multiline): Select the whole block section > Ctrl K U

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